Improved harmonic phase myocardial strain maps

Magnetic resonance tagging has proven a valuable too[ in the quantification of myocardial deformation. However, time-consuming postprocessing has disc ouraged the use of this technique in clinical routine. Recently, the harmon ic phase (HARP) technique was introduced for automatic calculation of myoca rdial strain maps from tagged images. In this study, a comparison was made between HARP instantaneous strain maps calculated from single tagged images (SPAMM) and those calculated from subtracted tagged images (CSPAMM). The p erformance was quantified using simulated images of an incompressible cylin der in the 'end-systolic' state with realistic image contrast and noise. Th e error in the second principal stretch ratio was 0.009 +/- 0.032 (mean +/- SID) for the SPAMM acquisition, and 0.007 +/- 0.016 for CSPAMM at identica l contrast-to-noise ratio. Furthermore, differences between the methods wer e illustrated with in vivo strain maps. Those calculated from CSPAMM images showed fewer artifacts and were less sensitive to the choice of cut-off fr equencies in the HARP band-pass filter. A prerequisite for the method to be come practical is that the CSPAMM images should be acquired in a single bre athhold. (C) 2001 Wiley-Liss, Inc.